Indium Gallium Zinc Oxide (IGZO) has become a research hotspot about oxide semiconductor materials at present, and its carrier mobility can reach up to 10 cm/Vs, which is above ten times larger than that of amorphous silicon. As for the panels of a large area and the panels of ultra-precision, it is possible that the response speed is increased favorably and the size of Thin Film Transistors (TFTs) is decreased with application of this material. Currently, this material has been widely used in Organic Light-Emitting Diode (OLED) display or Liquid Crystal Display (LCD). However, IGZO material is susceptible to external conditions such as water vapour, oxygen, etc., and this leads to degrades in material characteristics.
As to typical back panels (i.e., array substrates), what are currently in mass production are mainly of Low Temperature Poly Silicon (LTPS) and they have been in mass production by Samsung Corporation, but it is necessary that a great deal of modification be conducted upon existing equipments and investment on equipments be increased owing to the application of an ELA process. OLED back panels employing oxide semiconductor materials mostly adopt a top-gate structure, and impact of a source-drain (SD) etching solution on IGZO material can be avoided by using an etch stop layer technology. The number of mask processes (or a patterning processes) in the method of manufacturing the array substrate is usually six to seven.